Thermal storage capacity and tank orientation

[pwschiller]

I recently purchased two used 1000 gallon propane tanks. I plan on purchasing a wood boiler (probably 35kW or 40kW) and installing it along with storage in my workshop that will be built next year. The wood boiler and storage will be integrated with my existing oil boiler (in the house) as a backup and will be able to supply heat to both buildings. My design loss for the shop and house combined is around 55000 BTU/hr. I know that I really only need to use one of the 1000 gallon tanks for storage, but I'm wondering what people's thoughts are on having 2000 gallons of storage for the increased flexibility it would provide. Keeping the second tank would probably cost me around $1000 including the additional insulation and piping.

My other question relates to the placement of the tank(s). The workshop will have a basement. The tanks could either be horizontal in the basement of the shop, in which case they wouldn't take up any floor space that I care about, or they could be placed vertically, where they would take up a bit of main floor space in the corner of the shop. If I only used one of the two tanks, I think that I would be more inclined to have the tank vertical. The boiler will go on the main floor of the shop. How much better would it be to have the tank(s) oriented vertically?

Pete

 

[Chris Hoskin]

I'd rather see you spend the extra money on a larger output boiler with a single 1000 gallon tank than a smaller boiler with 2x1000 tanks. To me it is much more convenient to run one load of wood through a 50kW boiler to bring 1000 gallons back up to temp than it is to run two or three (or four?) loads in a row through a 30kW boiler to bring 2000 gallons back up to temp.


My gut reaction is absolutely go vertical with the single 1000. I don't have any data to quote, but I think all would agree that stratification is good and a vertical tank stratifies better than a horizontal tank. I don't think you'll have too much trouble selling the second LP tank right here if you wanted to.

sounds like a cool project, keep us posted.

 

[jimbom]

Vertical in the basement with three foot or so up into the shop. Advantages of vertical without cost of structural to support an 9000 pound point load on the shop floor. Access to dip tubes and connections on the top of the tank are at a convenient height in the shop. Earthquake restraint provided by shop floor structure, so expensive bolt down restraint not required to resist overturning. Bottom of tank restraint need only resist translation. Space above the tank available for use in the shop. YMMV